全文获取类型
收费全文 | 44378篇 |
免费 | 7673篇 |
国内免费 | 5870篇 |
专业分类
化学 | 31973篇 |
晶体学 | 513篇 |
力学 | 2627篇 |
综合类 | 375篇 |
数学 | 5255篇 |
物理学 | 17178篇 |
出版年
2024年 | 151篇 |
2023年 | 860篇 |
2022年 | 1543篇 |
2021年 | 1672篇 |
2020年 | 1758篇 |
2019年 | 1814篇 |
2018年 | 1561篇 |
2017年 | 1449篇 |
2016年 | 2134篇 |
2015年 | 2182篇 |
2014年 | 2640篇 |
2013年 | 3255篇 |
2012年 | 3947篇 |
2011年 | 3983篇 |
2010年 | 2805篇 |
2009年 | 2782篇 |
2008年 | 3014篇 |
2007年 | 2677篇 |
2006年 | 2455篇 |
2005年 | 2042篇 |
2004年 | 1567篇 |
2003年 | 1287篇 |
2002年 | 1388篇 |
2001年 | 1089篇 |
2000年 | 966篇 |
1999年 | 985篇 |
1998年 | 781篇 |
1997年 | 718篇 |
1996年 | 716篇 |
1995年 | 611篇 |
1994年 | 476篇 |
1993年 | 452篇 |
1992年 | 343篇 |
1991年 | 316篇 |
1990年 | 297篇 |
1989年 | 251篇 |
1988年 | 186篇 |
1987年 | 135篇 |
1986年 | 134篇 |
1985年 | 129篇 |
1984年 | 75篇 |
1983年 | 68篇 |
1982年 | 68篇 |
1981年 | 40篇 |
1980年 | 18篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1972年 | 8篇 |
1957年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Let p ∈ [1, ∞), q ∈ [1, ∞), α∈ R, and s be a non-negative integer. Inspired by the space JNp introduced by John and Nirenberg(1961) and the space B introduced by Bourgain et al.(2015), we introduce a special John-Nirenberg-Campanato space JNcon(p,q,s) over Rn or a given cube of R;with finite side length via congruent subcubes, which are of some amalgam features. The limit space of such spaces as p →∞ is just the Campanato space which coincides with the space BMO(the space of functions with bounded mean oscillations)when α = 0. Moreover, a vanishing subspace of this new space is introduced, and its equivalent characterization is established as well, which is a counterpart of the known characterization for the classical space VMO(the space of functions with vanishing mean oscillations) over Rn or a given cube of Rn with finite side length.Furthermore, some VMO-H1-BMO-type results for this new space are also obtained, which are based on the aforementioned vanishing subspaces and the Hardy-type space defined via congruent cubes in this article. The geometrical properties of both the Euclidean space via its dyadic system and congruent cubes play a key role in the proofs of all these results. 相似文献
2.
Paired single residue‐transposed Lys‐N and Lys‐C digestions for label‐free identification of N‐terminal and C‐terminal MS/MS peptide product ions: ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry and tandem mass spectrometry for peptide de novo sequencing 下载免费PDF全文
3.
4.
5.
JPC – Journal of Planar Chromatography – Modern TLC - A new high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous estimation of... 相似文献
6.
在中国科学技术大学夏季学期的研究型实验课程"化学科研基础训练"中开设"壳聚糖的制备与表征"综合实验,以龙虾壳为原料,通过除蛋白、脱盐、脱色、脱乙酰等一系列反应,制备得到目标产物壳聚糖。运用红外光谱、核磁共振仪、黏度法、滴定等对产品的结构及性能进行表征。 相似文献
7.
8.
Synthesis and Photophysical Properties of a Sc3N@C80‐Corrole Electron Donor–Acceptor Conjugate 下载免费PDF全文
Bin Liu Hongyun Fang Prof. Xiaofang Li Wenting Cai Lipiao Bao Marc Rudolf Fabian Plass Prof. Louzhen Fan Prof. Xing Lu Prof. Dirk M. Guldi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):746-752
Embedding endohdedral metallofullerenes (EMFs) into electron donor–acceptor systems is still a challenging task owing to their limited quantities and their still largely unexplored chemical properties. In this study, we have performed a 1,3‐dipolar cycloaddition reaction of a corrole‐based precursor with Sc3N@C80 to regioselectively form a [5,6]‐adduct ( 1 ). The successful attachment of the corrole moiety was confirmed by mass spectrometry. In the electronic ground state, absorption spectra suggest sizeable electronic communications between the electron acceptor and the electron donor. Moreover, the addition pattern occurring at a [5,6]‐bond junction is firmly proven by NMR spectroscopy and electrochemical investigations performed with 1 . In the electronically excited state, which is probed in photophysical assays with 1 , a fast electron‐transfer yields the radical ion pair state consisting of the one‐electron‐reduced Sc3N@C80 and of the one‐electron‐oxidized corrole upon its exclusive photoexcitation. As such, our results shed new light on the practical work utilizing EMFs as building blocks in photovoltaics. 相似文献
9.
This study is concerned with a new,explicit approach by means of which forms of the large strain elastic potential for multiaxial rubberlike elasticity may be obtained based on data for a single deformation mode.As a departure from usual studies,here for the first time errors may be estimated and rendered minimal for all possible deformation modes and,furthermore,failure behavior may be incorporated.Numerical examples presented are in accurate agreement with Treloar's well-known data. 相似文献
10.